Power Switch Fault Signatures in a Full Bridge DC/DC Converter of PV System

Abstract

Photovoltaic power generation stations are remotely located. Surveys have shown that semiconductor power devices are prone to failure due to several stress factors. Redundancy based fault diagnosis schemes in such remote power stations help to automatically diagnose the faulty component. This will reduce time for fault diagnosis. For development of reliable fault diagnosis scheme, proper understanding of fault signatures is essential. This communication deals with examination of fault signatures at various test points in full bridge DC-DC converter. Fault signatures due to open circuit power switch faults in converter are studied here. A model for full bridge DC-DC converter with photovoltaic array as input source has been developed. Open circuit power switch fault is introduced in model and its effect at several test points like across power switch, at transformer primary and secondary, at emitters of lower power switches, at inductor and at output is observed. Simulation results have shown that significant changes take place in the signals at test points. RMS/average value computation of these signatures and comparison with the signals in fault free states is an efficient way of diagnosing exact faulty power switch.